In a case where an image is watched via a display device, such as an existing theater screen, a computer monitor, a television receiver, the liquid crystal display (LCD) screen of a mobile phone, or the screen of a game machine, all viewers who are watching the display device must unconditionally watch only the same image. That is, in the case of a theater screen, for example, when a 3D image is being played on the theater screen, all viewers must wear 3D glasses and watch the 3D image, and cannot watch the same image in a 2D manner. The reason for this is that, in the case of a 3D image, a display device and 3D glasses are set such that a left image is viewed with a left eye and a right image is viewed with a right eye through the 3D glasses, thus making it impossible to watch a 2D image with 3D glasses worn by each viewer, and also making it impossible to view clear images without 3D glasses being worn because both a left image and a right image are simultaneously viewed with left and right eyes. This is a problem present in common among all display devices for playing 3D images using a polarization method, a shutter method, and an anaglyph method.
Further, when a television receiver is set to play an image on a specific channel, all viewers must watch the image on the set channel and cannot simultaneously watch an image on another channel via the same television receiver.
For example, in order to solve the above problem, in conventional technology, such as Korean Patent Registration No. 100757231 entitled “Method and apparatus for simultaneously watching multiple screens on a plurality of channels in a Digital Multimedia Broadcasting (DMB) mobile terminal,” the screen of a display device is divided into a main screen and a sub-screen and an image on a specific channel is played on the main screen while an image on another channel is being played on the sub-screen. However, such a scheme is also disadvantageous in that all viewers must watch the same format screen which is divided into the main screen and the sub-screen, and it is impossible for viewers to select only the main screen or the sub-screen and simultaneously watch the selected screen depending on their preferences, and in that a display area is separated into the main screen and the sub-screen and then a viewing experience is deteriorated.
In order to solve the above problem of the conventional technology, Korean Patent Application No. 10-1999-0051191 entitled “Apparatus for simultaneously playing various images” (this has since been extinguished) proposes an apparatus for allowing viewers to select and watch only desired images while simultaneously playing the various images. However, this technology is problematic in that a storage medium in which various types of images are alternately arranged on a frame basis is required, and is also problematic in that an implementation scheme for a sound output means for selectively outputting only the sounds of an image selected by an image selection means is not described, thus making it impossible to check whether this technology is realizable.
Further, Korean Patent Application No. 10-2004-0081180 entitled “Apparatus and method for playing various images (request for examination has not been made)” proposes an apparatus capable of playing various images. However, this technology is problematic in that it must include the step of manufacturing various images while allowing two or more images to alternately emerge on a frame basis, and in that a scheme for operating and implementing a polarization shutter glasses unit required to view various images using a polarizing filter is not described, thus making it impossible to check whether this technology is realizable.
Furthermore, Korean Patent Application No. 10-2004-0085890 entitled “Apparatus for playing two types of images” proposes an apparatus capable of playing various types of images. However, this technology is disadvantageous in that it requires a storage medium in which two types of images are stored in such a way as to arrange a first image in odd fields and a second image in even fields, and is problematic in that a play means for simultaneously playing the images stored in the storage medium is not described in detail, and a detailed implementation scheme for a sound output means for selectively outputting only the sounds of an image selected by an image selection means is not described, thus making it impossible to check whether this technology is realizable.
Meanwhile, a principle by which a 3D image is watched on a display device, such as an existing theater screen, a computer monitor, a television receiver, the LCD screen of a mobile phone, or the screen of a game machine, is that a left-eye image and a right-eye image for the 3D image are displayed using different time synchronization characteristics (hereinafter referred to as a ‘time division scheme’), different polarization characteristics (hereinafter referred to as a ‘polarization division scheme’) or different color characteristics (hereinafter referred to as a ‘color division scheme’), and that a viewer wears shutter glasses in the case of the time division scheme, polarized glasses in the case of the polarization division scheme, and colored glasses in the case of the color division scheme, depending on the display schemes, and so only a left-eye image passes through a left-eye lens and only a right-eye image passes through a right-eye lens, thus enabling the 3D image to watched.
In this case, in accordance with the above-described principle for displaying and watching 3D images, all viewers watch the same image. That is, in the case of, for example, a theater screen, when a 3D image is being played on the theater screen, all viewers watch only the corresponding 3D image with 3D glasses worn by the viewers. Further, when a television receiver is set to play an image on a specific channel, all viewers must watch the image on the set channel.
Conventional technology devised to solve this problem includes technology (Korean Patent No. 10-0757231, hereinafter referred to as a ‘screen division scheme’) for dividing the screen of a display device into a main screen and a sub-screen and playing an image on a specific channel on the main screen while playing an image on another channel on the sub-screen, time-division-based various image playing technology (U.S. Patent Publication No. US 2010/0079585) for displaying different images on the same screen in synchronization with different times, and allowing viewers to wear shutter glasses switched on/off in synchronization with desired images and to watch the desired images, and polarization division- or color division-based various image playing technology (Korean Unexamined Patent Publication No. 2002-0021204 and Japanese Unexamined Patent Publication No. 2007-178582) for displaying different images on the same screen in different polarizations or in different colors and allowing viewers to wear polarized glasses or colored glasses, which are designated to pass only desired images, and to watch the desired images. All of these conventional technologies propose display methods of simultaneously watching a plurality of 2D images, but the screen division scheme is problematic in that a screen is separated into a main screen and a sub-screen, thus deteriorating a viewing experience, and the various image playing technologies based on the time division scheme, the polarization division scheme, and the color division scheme cannot be applied to display methods of simultaneously watching a plurality of 3D images, or simultaneously watching a plurality of 2D and 3D images.
Furthermore, the conventional schemes for watching 3D images are limited in that compatibility between a 3D display device and 3D glasses is decreased, and then only a specific scheme-based display device can be watched using specific scheme-based 3D glasses. That is, by using polarized glasses, only a polarization division-based display device can be watched and other scheme-based display devices cannot be watched, and by using shutter glasses, only a time division-based display device can be watched, and other scheme-based display devices cannot be used to watch 3D images. Further, by using colored glasses, only a color division-based display device can be watched, and other scheme-based display devices cannot be watched.